This invention relates generally to downhole tools for drilling wellbores. More particularly, this invention relates to downhole drilling tools capable of supporting gyroscopic tools for use in downhole operations.
The downhole drilling of wellbores, such as oil wells, involves extreme operating conditions for drilling equipment. Downhole drilling involves high temperatures, high pressure and rigorous physical impact. Much of the drilling occurs at extreme depths into the earths surface or deep below the sea bottom.
Dowhole devices, are often used in drilling operations to perform various tasks, such as monitoring wellbore conditions, operating the drilling tool and communicating with the surface. Many such devices have intricate electrical connections and instrumentation which have difficulty adapting to the wellbore conditions. The gyroscope, or xe2x80x9cgyro,xe2x80x9d is one such tool used in downhole operations to perform tasks, such as determining downhole orientation.
Various devices have been developed to support gyroscopes within the drilling operation. For example, U.S. Pat. No. 5,507,348 issued to Scientific Drilling International discloses an apparatus for supporting instrumentation in a drill collar using elastomeric fins. While such developments may have provided techniques for supporting gyroscopes along a drilling tool, there remains a need to further adapt the gyroscope to the wellbore environment.
It is desirable to provide a means for protecting the gyroscope, support the gyroscope and enhance its ability to perform the desired tasks. It is further desirable to provide a system which allows easy loading and/or removal of the gyroscope into the drilling tool, while providing a packaging system that reduces shock and vibration, isolates the gyro from high pressures, and keep the gyro clean. An easy entry and exit system is needed for fast access to the gyro, preferably without taking the entire housing out of the collar or getting the gyro dirty. Thus, the gyroscope could be assembled at the rig. To meet these and other needs, the present invention has been developed.
A real time packaging system for a gyroscope (gyro) in a down-hole drilling tool is provided. The packaging system applies to gyroscopes used in the oilfield industry (ie. Rate-Gyros). The gyroscope is typically used during the drilling process for performing various downhole operations, such as providing down-hole orientation.
The packaging system is intended to permit the gyroscope and related downhole tool to perform under the severe drilling environments of the oilfield industry. The system allows a gyro to operate under high temperature, high pressure, and high shock or vibration and reduce the impact of such side effects to the gyro mechanism. In addition, the system allows for fast packaging procedures while maintaining the gyro clean and dry at all times.
The packaging system is positioned within a downhole drilling tool and lowered downhole into a wellbore for performing drilling operations. The packaging system is in a drill collar, and houses the gyroscope. The packaging system includes a housing for the gyro and one or more centralizers to support the housing within the drill collar. The packaging system may also be provided with a down-hole end cap, an up-hole endcap, and a loading device.
The packaging system may be either integrally formed within a drill collar, or positioned therein. The drill collar is then connected, typically threadably connected, to the remainder of the downhole tool. The tool is provided with a loading device which retains the housing in the collar. In addition, the system may also be provided with a gyro compression mechanism that is capable of holding wires to provide power and communication while compressing the gyro to isolate it from shock or vibration.
In one aspect, the invention relates to a downhole drilling tool for drilling a wellbore into an earth formation. The drilling tool has a drill string with a drill bit at an end thereof. The downhole drilling tool comprises a drill collar connectable to the drill string, a housing positionable within the drill collar, a gyroscope sealably positionable within the housing; and at least one centralizer positionable between the housing and the drill collar whereby the housing is supported in the drill collar. The drilling tool may be provided with a telemetry system, such as the xe2x80x9cPOWERPULSE(trademark)xe2x80x9d unit available from the assignee of the present application, for communicating uphole.
In another aspect, the invention relates to an apparatus for supporting a gyroscope in a drill collar of a downhole drilling tool. The apparatus comprises a housing adapted to receive a gyroscope and at least one centralizer for supporting the housing within the drill collar whereby the gyroscope is protected from downhole conditions. The housing is sealingly positionable within a drill collar. The apparatus may also comprise a downhole end cap; an uphole end cap; and a gyro compression mechanism capable of providing axial support for the gyroscope.
In yet another aspect, the invention relates to a method of supporting a gyroscope within a drill collar of a downhole drilling tool. The method comprises positioning a gyroscope within a housing in a drill collar, inserting a plug into a downhole end of the housing, and securing the gyroscope into the housing by applying axial compression to the gyroscope and locking the downhole end of the gyroscope in place.
Another method is provided for supporting a gyroscope within a drill collar of a downhole drilling tool, the drilling tool comprising a drill string connectable to the drill collar. This method comprises inserting a gyroscope into a housing between a first compression rod and a second compression rod, positioning the housing within the drill collar, and applying a compressive force to the gyroscope by advancing a plug into the housing whereby the gyroscope is compressed between the compression rods.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.